According to conventional techniques, a casing (case) of a mobile phone is formed by molding a synthetic resin such as a polycarbonate resin or an ABS resin. A folding mobile phone having a receiver side and a transmitter side coupled to each other by a hinge mechanism is taken as an example. A transmitter-side casing is composed of a front case having, on its surface, an operation portion, and a rear case that is arranged to make contact with the rear of the front case and has a battery containing portion therein.
In recent years, it has been increasingly desired to reduce the thickness of mobile phones and improve the appearance and usability thereof. Further reduction in the thickness of mobile phones requires reduction in size and thickness of individual parts of the mobile phone such as front cases, rear cases, batteries, printed circuit boards, and other electronic components. Further, there is an increasing trend in the use of a built-in antenna in a mobile phone in light of the appearance thereof. This requires an antenna to be efficiently housed in a small space within a casing.
A conventional antenna (built-in antenna) of a mobile phone has a structure in which antenna elements made of metal are integrally formed with a bar-shaped support member made of a synthetic resin, and is located in a rear case along the upper side of the inside surface thereof. An example of a mobile phone containing such an antenna therein is “F882iES” placed on the market by FUJITSU LIMITED.
Incidentally, a strap has conventionally been attached to a mobile phone in many cases. This is because such a strap helps a user to carry his/her mobile phone or to remove the same from his/her bag, or such a strap is attached as a mobile phone ornament. A casing, therefore, is provided with a strap retaining portion that projects into the casing, which reduces the internal space of the casing. The commercially available mobile phone described above has a strap retaining portion formed adjacent to an end of the upper side of a rear case. It is desired, however, to provide a strap retaining portion in the center of the upper side of a rear case to improve the usability and appearance of a mobile phone.
In such a case, however, the strap retaining portion is caused to project into a casing at the center of the upper side thereof. The strap retaining portion, thus, interferes with an antenna to be located in the position where the strap retaining portion projects.